1. Field of the Invention
The invention relates to a vehicle seat that is mounted in a vehicle, for example, a car.
2. Description of the Related Art
A vehicle seat usually includes a pad made of resin foam, for example, urethane foam, and a seat upholstery that covers the surface of the pad. Japanese Patent Application Publication No. 10-33297 (JP-A-10-33297) describes a pad which includes a first pad portion that is located under buttocks of a user and a second pad portion that is a portion of the pad other than the first pad portion. The first pad portion and the second pad portion are arranged next to each other. The second pad portion is made of urethane foam that is lower in density and higher in rebound elastic modulus than the first pad portion. The light second pad portion contributes to weight reduction of the pad as a whole. In addition, the first pad portion is used as a portion of the pad, which is located under the buttocks and therefore has a great influence on comfort of the user, and the second pad portion is used as a portion of the pad, which does not have a great influence on comfort of the user. With this arrangement, the comfort of the seat is appropriately maintained. Japanese Patent Application Publication No. 2006-75589 (JP-A-2006-75589) and Japanese Patent Application Publication No. 2005-74108 (JP-A-2005-74108) each describe a pad which includes a pad body and an fitted body that is fitted in a recess formed in the back face of the pad body and that is higher in hardness than the pad body.
However, the pad described in JP-A-10-33297 may cause discomfort to a user seated in the vehicle seat because the elastic deformation volume changes at the boundary between the first pad portion and the second pad portion. In contrast, the pad described in each of JP-A-2006-75589 and JP-A-2005-74108 provides a user with a higher level of comfort and holds the user more stably because a seating surface portion is soft and a back side portion is hard. However, there have been demands for lighter pads.